Update pom.xml and build jar instructions

.github/CONTRIBUTING.md

@@ -6,7 +6,7 @@ We welcome contributions! After all, this project started as a port of [another]
 
 For minor fixes (e.g., documentation improvements), feel free to submit a PR directly. If you would like to fix a bug or implement a new feature, please open an [issue](https://github.com/madiali/mips-emulator/issues/new/choose) first, and mention the issue in your PR.
 
-Once you make a PR, your code will be tested and built into a JAR automatically. You can download and test the generated artifact in the [Actions](https://github.com/madiali/mips-emulator/actions) tab. For more information, see [Build](#build).
+Once you make a PR, your code will be tested and built into a JAR automatically. You can download and test the generated artifact in the [Actions](https://github.com/madiali/mips-emulator/actions) tab. For more information, see [Build JAR](#build-jar).
 
 ## Dev setup
 
@@ -22,15 +22,15 @@ Dependencies are listed in [pom.xml](../pom.xml). This project has to work acros
 
 Use [Google Java format](https://plugins.jetbrains.com/plugin/8527-google-java-format) to format all code (4 spaces).
 
-## Build
+## Build JAR
 
 ### Automatic
 
-Building occurs automatically via a GitHub Action (see [build.yml](workflows/ci.yml)) that uses Maven. As long as users have a compatible Java version (17+, with JavaFX bundled), this JAR should work on all OS's and architectures (x86 and ARM64). However, we have in the past encountered compatibility issues with some OS/arch combinations, so it is best to test manually (e.g., on M1 macOS) before releasing.
+The JAR is automatically built via a GitHub Action (see [build.yml](workflows/ci.yml)) that uses Maven. As long as users have a compatible Java version (17+, with JavaFX bundled), this JAR should work on all OS's and architectures (x86 and ARM64). However, we have in the past encountered compatibility issues with some OS/arch combinations, so it is best to test manually (e.g., on M1 macOS) before releasing.
 
 ### Manual
 
-To build manually, go to IntelliJ and click on the Maven tab on the right. The file that we want will be at `target/dependency/mips-emulator-<version>-SNAPSHOT-jar-with-dependencies.jar`. The version is specified in [pom.xml](../pom.xml).
+To build the JAR manually, install `maven` on your system. Then run `mvn package`. The output JAR will be at `target/dependency/mips-emulator-<version>-SNAPSHOT-jar-with-dependencies.jar` and can be run with `java -jar`. The version is specified in [pom.xml](../pom.xml).
 
 ## Deploy
 

pom.xml

@@ -182,10 +182,14 @@
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-assembly-plugin</artifactId>
                 <configuration>
+                    <descriptorRefs>
+                        <descriptorRef>jar-with-dependencies</descriptorRef>
+                    </descriptorRefs>
                     <outputDirectory>${project.build.directory}/dependency</outputDirectory>
                 </configuration>
                 <executions>
                     <execution>
+                        <id>assemble-all</id>
                         <phase>package</phase>
                         <goals>
                             <goal>single</goal>
@@ -198,9 +202,6 @@
                                     </mainClass>
                                 </manifest>
                             </archive>
-                            <descriptorRefs>
-                                <descriptorRef>jar-with-dependencies</descriptorRef>
-                            </descriptorRefs>
                         </configuration>
                     </execution>
                 </executions>